This invention relates generally to pumps, and in particular to vaned impeller pump useful as an electric-motor-operated fuel pump for an automotive vehicle to pump liquid fuel from a fuel tank through a fuel handling system to an engine that powers the vehicle.
In an automotive vehicle that is powered by an internal combustion engine, fuel that may be pumped through a fuel handling system of the engine by an in-tank, electric-motor-operated fuel pump.
Examples of fuel pumps are shown in various patents, including U.S. Pat. Nos. 3,851,998; 5,310,308; 5,409,357; 5,415,521; 5,551,875; 5,601,308; and 5,904,468. Commonly owned U.S. Pat. Nos. 5,310,308; 5,409,357; 5,551,835; 5,375,971; and 5,921,746 disclose pumps of the general type to which the present invention relates, and such pumps provide certain benefits and advantages over certain other types of pumps. One benefit of such pumps is that a number of its parts may be fabricated from polymeric (i.e. plastic) materials.
Through the continuing development of such pumps, it has been discovered that the presence of certain particulate material in commercial fuel may abrade such synthetic materials and thereby encourage wearing of pump parts made of such materials. Because vanes of a plastic impeller of such a pump are quite small, and because running clearances between pumping chamber walls and such an impeller may also be small, it is believed desirable to reduce the extent of interaction of such particulate material with the internal pumping mechanism. Because an automotive vehicle manufacturer cannot at the present time reasonably rely on commercial fuel refiners to improve fuel purity, is has become incumbent on the vehicle manufacturer to find a solution.
The present invention relates to a solution for the situation just described. In this invention the or more grooves are provided in the seal surface between inlet and outlet, which is called the xe2x80x9cstrip areaxe2x80x9d. The grooves extend radially outward, and the length is about the same width as flow channels. The width of the channel is about 1 mm, and the depth of the grooves is about 1.0-1.5 mm. Each groove has a smooth upward ramp to match the vortex path, and reduce flow losses. The shape of the grooves can be flat in the bottom, circular, or elliptical shape.
There are three functions of this invention so called xe2x80x9cleakage prevent groovesxe2x80x9d. They reduce the contact surface of the impeller/cover, and reduce the friction torque; the grooves match the vortex path, clean the contamination in the area, and reduce the chance of wear between impeller/cover. If impeller/cover does wear because of the contamination, the radial directional grooves act like seal grooves and reduce the leakage between inlet/outlet.
Other general and more specific aspects will be set forth in the ensuing description and claims.